Sorption drying system

ABSTRACT

A sorption drying system for dehumidification of a moist gas stream, includes a mass of absorbing material, a moist gas stream arranged to flow through at least a part of the absorbent mass, and a heated stream of regeneration gas arranged to flow through at least a part of the absorbent mass. The sorption drying system further includes structure for deflecting a part of the dehumidified gas stream after flowing through the absorbent mass, a cooler for cooling the deflected dehumidified gas stream, and structure for returning the cooled deflected dehumidified gas stream to the moist gas stream at the inlet into the absorbent mass. At least a part of the cooled deflected dehumidified gas stream is arranged to flow through the absorbent mass in a channel separated from the moist gas stream.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. Ser. No. 14/411,639,entitled “A Sorption Drying System”, filed Dec. 29, 2014, now U.S. Pat.No. 9,616,380, which claims priority under 35 USC § 119 fromPCT/SE2013/050843, filed Jul. 1, 2013 and claiming priority to SE1250744-8, filed Jun. 29, 2012. The subject matter of each of theabove-noted applications is incorporated by reference in theirentireties.

TECHNICAL FIELD

The present invention concerns a sorption drying system fordehumidification of a moist gas stream comprising a mass of absorbingmaterial, a moist gas stream arranged to flow through at least a part ofthe absorbent mass, and a heated stream of regeneration gas arranged toflow through at least a part of the absorbent mass. In a second aspect,the present invention concerns a method for dehumidification of a moistgas stream in such a sorption drying system comprising a mass ofabsorbing material.

BACKGROUND OF THE INVENTION

Systems for dehumidification or drying of moist gas streams are knownsince long. Examples of such systems are found in, among others, U.S.Pat. No. 4,701,189 and US 2005/0235827, which disclose rotary dryingwheels. The drying wheel contains a mass of absorbing or sorptivematerial (drying agent) that removes moisture from the gas stream by thevapor being absorbed. The moisture is picked up in the drying agent andthe dry gas stream is forwarded for the use in a process or the like.After a prolonged dehumidification, the drying agent will be saturatedwith moisture, and therefore it is required that the moisture has to bedriven out of the drying agent for enabling the drying to proceed. Thisis usually made by regeneration, i.e., that a heated gas stream passesthrough the drying wheel in an area separated from the passage of themoist gas stream. The heated air regenerates the drying wheelcontinuously, which thereby gives a continuous drying of the moist gasstream.

A problem of such drying wheels is that, upon absorption of vapor,latent heat in the gas stream is converted into sensible heat, i.e., theevaporation energy in absorption increases the temperature of the gasand drying agent, which impairs its absorption capacity. Likewise, alsothe regeneration increases the temperature of the drying wheel.

US 2011/0132191 and US 2012/0125198 disclose proposals of solutionswherein a separate gas stream for the cooling of the absorbing dryingagent flows through the drying wheel in a delimited zone or sectorseparated from the main flow of the gas to be dried and the regenerationflow. Disadvantages of these solutions are that they require anadditional flow for the cooling gas with associated equipment and thatthe available sector for the drying of the gas in the main flow isreduced, which impairs the capacity of the drying wheel. Anotherdisadvantage is that the cooling sector only cools the drying agent inthe beginning of its revolution; during the remaining part of therevolution, the drying agent is heated during the absorption.

JP 60-102919 discloses a system for dehumidification of air with highair humidity using a dehumidifying rotor, wherein a part of adehumidified air stream is passed through a heat exchanger rotor thatlowers its temperature, whereupon a part of this dehumidified cooled airis mixed with moist air in order to lower the air humidity of theincoming air that then is sent to the dehumidifying rotor. Adisadvantage of this system is that the cooled air does not essentiallycontribute to the lowering of the temperature of the rotor. Therefore,there is a need of developing systems and methods for improving theperformance of sorption dryers, particularly for use with high airhumidities.

SUMMARY OF THE INVENTION

The object of the present invention is to provide systems and methodsfor improving the performance of sorption dryers.

This is achieved by a sorption drying system for dehumidification of amoist gas stream, comprising a mass of absorbing material, a moist gasstream arranged to flow through at least a part of the absorbent mass,and a heated stream of regeneration gas arranged to flow through atleast a part of the absorbent mass. The sorption drying system furthercomprises means for deflecting a part of the dehumidified gas streamafter flowing through the absorbent mass, a cooler for cooling thedeflected dehumidified gas stream, and means for returning the cooleddeflected dehumidified gas stream to the inlet into the absorbent mass,at least a part of the cooled deflected dehumidified gas stream beingarranged to flow through the absorbent mass in a channel separated fromthe moist gas stream.

By reusing a part of the already dehumidified gas stream that has beencooled to lower the temperature in the absorbent mass, a lower, moreoptimal temperature for dehumidification is attained, where theabsorbent mass more efficiently absorbs the moisture in the gas stream.Simultaneously, the advantage is achieved that the supplied cooled gasstream contributes with less additional moisture, since it is alreadypartly dehumidified. If the balance between cooled deflecteddehumidified gas and moist gas is optimized, the drying performance isincreased in spite of the fact that flow rates of the gas(-es) throughthe absorbent mass may differ and/or be elevated. By separating at leasta part of the cooled deflected dehumidified gas stream from the moistgas stream, a controlled recirculation or return of the cooled deflecteddehumidified gas stream is achieved. This means that the flow rate orthe air flow of the cooled dehumidified gas stream can be increased sothat it efficiently cools down the absorbent mass.

In another embodiment, deflection of the dehumidified gas stream occursfrom an area on the outlet side of the absorbent mass that essentiallycorresponds to the area on the inlet side of the absorbent mass towardwhich the moist gas stream is directed. This means that the dehumidifiedgas stream is deflected from an area of the absorbent mass that ishumidity-saturated to a higher degree than the other areas, whichimpairs its absorption capacity. Then the part of the dehumidified gasstream that is allowed to pass without deflection comes from areas oflower degree of saturation, and thereby better absorption capacity,which gives an improved drying performance of the sorption dryingsystem.

In an alternative embodiment, the cooled dehumidified gas stream flowsthrough the absorbent mass in a channel separated from the moist gasstream by means of seals.

In a preferred embodiment, the means for deflection comprises a fan orpump situated between the outlet of the dehumidified gas stream from theabsorbent mass and the cooler

In an alternative embodiment, the means for deflection comprises a fansituated between the cooler and the inlet of the moist gas stream intothe absorbent mass.

In another preferred embodiment, the absorbent mass essentially is inthe form of a disc or rotor and is adapted to rotate about a centralaxis, the moist gas stream being adapted to flow through a first channelin the disc and the stream of regeneration gas being adapted to flowthrough a second channel in the disc, separated from the first channelby means of seals, and the channels essentially having the shape ofcircular sectors.

In an alternative embodiment, deflection of the dehumidified gas streamoccurs in a partial circular sector situated essentially immediatelyafter the circular sector of the stream of regeneration gas in thedirection of rotation of the absorbent disc. Alternatively, deflectionof the dehumidified gas stream occurs in a partial circular sectorsituated essentially immediately before the circular sector of thestream of regeneration gas in the direction of rotation of the absorbentdisc. Preferably, deflection occurs by a combination from both partialcircular sectors.

In another embodiment, the sorption drying system comprises a valvesituated at the outlet of the stream of regeneration gas from theabsorbent mass for regulating the pressure of the stream of regenerationgas.

In a preferred embodiment, the sorption drying system comprises a fanfor varying the flow of the stream of regeneration gas through theabsorbent mass.

In an alternative embodiment, the parts of the drying system thatcomprise the absorbent mass and its seals are built-in in an air-proofshell.

In a second aspect, the present invention concerns a method fordehumidification of a gas stream in a sorption drying system comprisinga mass of absorbing material, wherein the method comprises the steps of:flowing through at least a part of the absorbent mass by a moist gasstream; and flowing through at least a part of the absorbent mass by aheated stream of regeneration gas; deflecting a part of the dehumidifiedgas stream after flowing through the absorbent mass; cooling thedeflected dehumidified gas stream; and returning the cooled deflecteddehumidified gas stream to the moist gas stream at the inlet into theabsorbent mass.

Preferred embodiments of the method comprise features corresponding tothe features of the sorption drying system.

In a preferred embodiment, the method comprises the step of regulatingthe pressure of the stream of regeneration gas in such a way that thisis essentially equal to, however always lower than, the pressure of themoist gas stream.

According to yet another embodiment, there is provided a sorption dryingsystem for dehumidification of a humid gas stream. The system comprisesa mass of absorbing material having an inlet side and an outlet side;the inlet side being divided into three different inlet areas (A, B, C)wherein a heated regeneration gas stream is either directed to orcollected from a first inlet regeneration area (A), a deflecteddehumidified gas stream is directed to a second inlet area (B) and ahumid gas stream is directed to a third inlet area (C). The outlet sideis divided into four different outlet areas (a, b, c, d). A collectioncontainer is arranged on the outlet side of the absorbing material,collecting the regeneration gas stream from or directed the regenerationgas to a first outlet area (a), collecting a first part of the deflecteddehumidified gas stream from a second outlet area (b), collecting asecond part of the deflected dehumidified gas stream from a third outletarea (c) and directing the deflected dehumidified gas stream out fromthe drying system as a user dehumidified gas stream, collecting a thirdpart of the deflected dehumidified gas stream together with the humidgas stream, from a fourth outlet area (d). The first part of thedeflected dehumidified gas stream from the second outlet area (b)together with the third part of the deflected dehumidified gas streamand the humid gas stream from the fourth outlet area (d) is deflected asa recirculation to the second inlet area (B) as the deflecteddehumidified gas stream.

According to yet another aspect, there is provided a sorption dryingsystem for dehumidification of a humid gas stream. The system comprisesa mass of absorbing material having an inlet side and an outlet side,wherein the inlet side is divided into three different inlet areas (A,B, C). A heated regeneration gas stream is either directed to orcollected from a first inlet regeneration area (A), a deflecteddehumidified gas stream is directed to a second inlet area (B) and ahumid gas stream is directed to a third inlet area (C), the outlet sidebeing divided into four different outlet areas (a, b, c, d). Acollection container is arranged on the outlet side of the absorbingmaterial, collecting the first regeneration gas stream from or directedthe regeneration gas to a first outlet area (a), collecting a first partof the deflected dehumidified gas stream from a second outlet area (b),collecting a second part of the deflected dehumidified gas stream from athird outlet area (c) and directing the deflected dehumidified gasstream out from the drying system as a user dehumidified gas stream,collecting a third part of the deflected dehumidified gas streamtogether with the humid gas stream from a fourth outlet area (d). Thesorption drying system further comprises: a valve situated at an inletconnection or outlet connection for the stream of regeneration gas forregulating the pressure of the stream of regeneration gas, and/or avalve situated at the inlet side or outlet side of the mass of absorbingmaterial for the humid gas stream for regulating the pressure of thehumid gas stream.

According to yet another aspect, there is provided a method fordehumidification of a gas stream in a sorption drying system comprisinga mass of absorbing material having an inlet side and an outlet side.The method comprises the steps of: directing a humid gas stream into themass of absorbing material through a first end portion connectionarranged on the inlet side of the mass of absorbing material, whereinthe first end portion connection is shaped so that the humid gas streamis directed inward toward a sector-shaped area of the mass of absorbingmaterial, such that the humid gas stream flows through a part of themass of absorbing material corresponding to the sector defined by thefirst end portion and is dehumidified; directing a heated stream ofregeneration gas through a regeneration sector of the mass of absorbingmaterial. The regeneration sector is separated from the sector definedby the first end portion connection; deflecting the dehumidified gasstream from the outlet side of the mass of absorbing material by meansof a collection container arranged on the outlet side of the mass ofabsorbing material to cover a sector of the mass of absorbing materialthat is essentially as large as the sector defined by the first endportion connection. The collection container is placed so that thesector covered by the collection container essentially corresponds tothe sector defined by the first end portion connection on the inlet sideof the mass of absorbing material toward which the humid gas stream isdirected; and returning the dehumidified gas stream to the inlet side ofthe mass of absorbing material by means of a second end portionconnection arranged on the inlet side of the mass of absorbing materialseparate from the first end portion connection for the humid gas stream.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in a schematic view a sorption drying system having acooled recirculation flow according to the present invention;

FIG. 2 shows in a schematic view an absorbent disc according to thepresent invention;

FIG. 3 shows in a schematic view a sorption drying system with regulatedgas stream pressure according to the present invention;

FIG. 4 shows in a perspective view a sorption drying system having acooler according to a first embodiment of the present invention;

FIG. 5 shows in a perspective view a sorption drying system according toa first embodiment of the present invention;

FIG. 6 shows in a perspective view a sorption drying system according toa first embodiment of the present invention;

FIG. 7 shows a detail of the sorption drying system in FIG. 4;

FIG. 8 shows in a perspective view a sorption drying system according toa second embodiment of the present invention;

FIG. 9 shows a detail of the sorption drying system in FIG. 8;

FIG. 10 shows a detail of a sorption drying system in accordance withanother embodiment; and

FIG. 11 shows another detail of the various gas stream within thesorption drying system of FIG. 10.

DETAILED DESCRIPTION

Below, the sorption drying system will be described more in detail,reference being made to the figures. However, the invention should notbe considered limited to the embodiment or embodiments shown in thefigures and described below, but may be varied within the scope of theclaims.

The concepts “drying” and “dehumidification” may be interpreted in astrict way as a process to remove water from an air stream or gasstream. In the present description, however, the concepts should beinterpreted in a wider meaning to remove or separate an absorbableand/or condensable component from an air stream or gas stream. Examplesof such components that fall within the scope of the present inventionare volatile organic compounds (VOCs), carbon dioxide, and/or carbonmonoxide. The invention is, however, not limited to these.

FIG. 1 shows a schematic illustration of a sorption drying systemaccording to the present invention. A mass 1 of absorbing or sorptivematerial is adapted to be flowed through by a moist gas stream 2 to bedehumidified. Preferably, the absorbent mass 1 is adapted to rotate inthe direction of the arrow, thereby being a rotor dryer. In analternative embodiment of the invention, the absorbent mass 1 is part ofa column dryer having a stationary absorbent mass 1 that is flowedthrough by a moist gas stream. In the following, the description will bedirected to a rotary absorbent mass 1, a so-called drying wheel or rotordryer. The corresponding features are, however, also applicable to acolumn dryer, which in the cooling of absorbent mass also is embraced bythe present invention. The cooling may be carried out according to thesame recirculating principle, but also by alternative cooling methodswherein the temperature rise of the absorbent mass is counteracted, forinstance by a cooling coil in the absorbent mass or an air stream thatpasses the column or the tube without physical contact, similar to across flow heat exchanger with thermal contact.

The absorbing material comprises silica gel, molecular sieves (alsocalled mol sieves), zeolites, or a combination of the same. Theabsorption material is, however, not limited to these, but also othersuitable absorbents are feasible. In a preferred embodiment, thesorptive material and its absorption capacity is adapted according tothe change of the relative humidity of the moist gas stream in thedirection of the gas stream through the absorbent mass 1. Thetemperature increases and the relative air humidity decreases with thedistance from the inlet to the absorbent mass 1. For instance, theabsorbent mass may comprise silica gel (SiO₂) near the inlet and molsieve near the outlet.

During the throughflow of the absorbent mass 1, the moist gas stream 2will be dehumidified by absorption, after which a dehumidified gasstream flows out of the absorbent mass on the other side.

For the regeneration of the absorbent mass 1, i.e., drive out themoisture from the absorbent mass, a stream of regeneration gas 3 isarranged to flow through the absorbent mass in the opposite direction ofthe moist gas stream. It is also within the scope of the invention thatthe stream of regeneration gas 3 flows through the absorbent mass 1 inthe same the direction as the moist gas stream. In case the sorptiondrying system comprises a column dryer with stationary absorbent mass 1,the same is flowed through alternately by a moist gas stream fordehumidification and a stream of regeneration gas to drive out themoisture from the absorbent mass 1.

The stream of regeneration gas 3 is heated by a heater 14 that may beplaced in direct connection to the absorbent mass 1. It is also feasiblethat the heater 14 is situated further from the absorbent mass 1, orthat the stream of regeneration gas 3 is heated in another way, forinstance by the use of waste heat from a process wherein the sorptiondrying system is included.

The absorbent mass 1 is preferably formed as a disc or rotor whereinchannels or passages 10, 11 for the moist gas stream and the stream ofregeneration gas 3 occupy different, separated circular sectors, whichis illustrated in FIG. 2. The channels 10, 11 are separated by means ofradially arranged seals. The circular sectors 10, 11 do not define fixedchannels in the disc of the absorbent mass 1, but the passage of thechannels through the disc varies according to the rotation of the disc.Thus, the circular sectors 10, 11 delimit the instantaneous areas orzones of the flow of the gas streams 2, 3 into and out of the absorbentmass 1.

In order to counteract the impaired absorption capacity of the absorbentmass 1 due to heating as a consequence of moisture absorption, and inorder to increase the number of passages through the absorbent mass 1,the sorption drying system comprises means 4 for deflecting a part ofthe dehumidified gas stream that flows out of the absorbent mass 1. Themeans 4 may, for instance, comprise a fan or a pump 8, 9 that sucks in apart of the dehumidified gas stream into a separate conduit or channel 4and leads it past a cooler 5. The cooler 5 may, for instance, comprise aheat exchanger, a heat pump, water-glycol batteries, a heat pipe, or acombination of the same. The deflected dehumidified gas stream is cooledby the cooler 5, whereupon the cooled dehumidified air is returned tothe moist gas stream at its inlet into the absorbent mass 1 via aconduit 6, 7. Thus, a cooled recirculation flow is formed thatefficiently cools the absorbent mass 1 without the supply of a separatecooling gas in a separate circular sector of the absorbent mass 1.Another advantage that is achieved is that the heat taken from thedeflected dehumidified gas stream may be used to preheat the stream ofregeneration gas 3.

The fan 8, 9 that deflects a part of the dehumidified gas stream may,for instance, be situated between the outlet of the dehumidified gasstream from the rotary absorbent mass and the cooler 5, and/or betweenthe cooler 5 and the inlet of the moist gas stream into the rotaryabsorbent mass. In the latter case, the cooled dehumidified air mayadvantageously be directed to the intake of the fan 9, so as to then besupplied to the inlet of the absorbent mass 1 for the moist gas stream2. It is then possible to get along without the fan 8 depending onavailable pressures and desired flow in the deflected gas stream.

Preferably, the deflected dehumidified air is taken from an area orpartial circular sector wherein the air is most moist. It may be from apartial circular sector 10 a essentially immediately after the circularsector of the stream of regeneration gas 3 in the direction of rotationof the disc, when the absorbent mass 1 is warm and possibly moist.Another alternative is to deflect the air from a partial circular sector10 b essentially immediately before the circular sector of the stream ofregeneration gas 3 in the direction of rotation of the disc, when theabsorbent mass 1 is to a higher degree humidity-saturated than in theother areas of the disc. It is also within the scope of the invention tocombine deflection of a dehumidified gas stream from both the previouslydescribed partial circular sectors. The part of the dehumidified gasstream that is driest, i.e., from the partial circular sector 10 betweenthe two above-mentioned partial circular sectors 10 a, 10 b, is allowedto proceed through the sorption drying system without deflection. Thedeflection sectors may be delimited and separated by means of rigidseals, but may also be made without rigid seals, the air being deflectedin the vicinity of the two moist partial circular sectors 10 a, 10 bdescribed above by a negative pressure formed by the fan 8, 9 in theconduit 4 that leads to the cooler 5.

For reducing the energy consumption of the sorption drying system, theheater power, the heater flow, the rotor speed, the cooled recirculationflow, and its cooling may be adapted based on the currentdehumidification need. This can be made with knowledge about flows,inlet moist, and target moist of the dry air. A simpler variant of thisis a temperature sensor at the inlet, when it is known that the air doesnot have higher air humidity than what the temperature allows, since theheater power of the dehumidifier, the heater flow, rotor speed, thecooled recirculation flow, and its cooling are controlled based onknowledge about its performance under different conditions. Atemperature sensor is cheaper and more stable than a moist sensor.

Another problem that arises in the sorption drying system is leakagebetween the moist gas stream and the stream of regeneration gas 3 sincethe seals that define and separate the channels of the gas streams arenot absolutely tight. This leakage between the gas streams results ininferior dehumidification if the air from the regeneration flow forexample leaks over to the dry air flow. Occasionally, the gascomposition between the different flows may be in such a way that theleakage has to be controlled. Occasionally, the pressure ratios may inaddition be variable because of connected equipment in channels andchanged flows.

A solution to this problem is to actively monitor and regulate thepressure of the stream of regeneration gas 3 and/or the moist gas stream2 to counteract the leakage. The pressure of the gas streams is measuredby means of suitable pressure transducers or gauges deployed in the flowof the respective gas stream through the sorption drying system. FIG. 3shows a valve 12, arranged at or connecting to, for instance, the outletof the stream of regeneration gas 3 from the absorbent mass that isadapted to regulate the pressure of the stream of regeneration gas 3 byadjusting the pressure drop through the valve 12. It is also within thescope of the present invention that the valve 12 is arranged at theinlet of the stream of regeneration gas 3 into the absorbent mass 1. Thepressure of the stream of regeneration gas 3 is then regulated in such away that it always is a little lower than the pressure of the moist gasstream. In other words, the valve 12 creates precisely so much pressurein the stream of regeneration gas 3 so that its pressure is essentiallyequal to the pressure of the moist gas stream, however always lower.Thereby, leakage from the stream of regeneration gas 3 to the moist gasstream is prevented, at the same time as leakage in the oppositedirection is minimized. The reason for a certain leakage being allowedfrom the moist gas stream to the stream of regeneration gas 3, but notvice versa, is that the air humidity of the dry air is not increased;alternatively that air from the regeneration side does not contaminatethe dry air with its composition.

Because of the activity of the valve 12, the flow of the stream ofregeneration gas 3 is affected. Therefore, the flow may need to beadjusted, for instance by means of a regulated fan 13.

Another further problem that may arise is that a required rise of thepressures in the gas streams causes leakage through the peripheral sealsof the sorption drying system. In a preferred embodiment, the part ofthe drying system that comprises the rotary absorbent mass 1 and itsseals is built-in in an air-proof shell (not shown), inside which theleakage air builds up a pressure that makes the leakage to stop or beminimized. Moreover, should the occasion arise, when the leakage insidethe shell passes further into the other air stream, it passes in acontrolled way in the correct direction (as a consequence of thepressure control by the valve system). This construction eliminateslosses out from the drying system.

FIGS. 4-6 show in a perspective view a sorption drying system accordingto a first embodiment of the present invention. Reference designationsof the corresponding features in FIG. 1 and FIG. 3 have been kept. Here,the absorbent mass 1 in the form of a drying rotor is contained in acylindrical housing 15. The housing 15 has an inlet side or inlet endportion 16 and an outlet side or outlet end portion 17. The gas stream 2to be dehumidified or separated from another gas is directed into thedrying rotor through a first, upper end portion connection 18 on theinlet side 16. The first end portion connection 18 is funnel-shaped andis shaped so that the gas stream 2 is directed inward toward anapproximated circular sector-shaped area of the drying rotor. The inletside 16 has also an outlet connection 20 for the stream of regenerationgas 3, which passes against the current through a regeneration sector 11of the drying rotor. It is also feasible to allow the stream ofregeneration gas 3 to pass the drying rotor with the current, whereuponthe connection 20 then constitutes the inlet for the stream ofregeneration gas 3.

The drying rotor rotates clockwise as seen from the inlet side 16. Themoist air in the gas stream 2 is then roughly brought into a part of thedrying rotor that is about to enter the regeneration sector 11. In thisapplication of controlled recirculation, this has the advantage that themoist air is pre-dried, since a large concentration difference betweenthe moist gas stream 2 and the drying rotor is utilized by using a moresaturated part of the drying rotor.

On the outlet side 17, the dehumidified gas stream is received by thedeflection means 4 in the form of a collection container 19. Thecollection container 19 covers a sector of the drying rotor that isessentially as large as, or preferably greater than, the sector that themoist gas stream 2 roughly is brought towards through the inletconnection 18, this in order to reliably capture essentially alldehumidified gas, but also to increase the amount of gas that isforwarded to the cooler 5. The amount of gas increases the cooling anddecreases heating per passage through the drying rotor. The collectioncontainer 19 is placed so that the sector that is covered by thecollection container 19 essentially corresponds to the inlet connection18 for the moist gas stream. This to guarantee that deflection of thedehumidified gas stream takes place from an area on the outlet side 17of the absorbent mass 1 that essentially corresponds to the area on theinlet side 16 of the absorbent mass 1 toward which the moist gas stream2 is directed.

The collection container 19 may also have a second collection sector 21arranged immediately after the regeneration sector 11, where the dryingrotor is warm and thereby dries poorly and may also after steam. Theoutlet side 17 has also an inlet 23 for the stream of regeneration gas 3in case a counter-current regeneration is used, and vice versa for aconcurrent regeneration.

The dehumidified gas that is collected in the collection container 19 issucked into the cooler 5 through the tube 22 by means of, for instance,a fan (not shown) that has been described above. The dehumidified gas iscooled and reintroduced on the inlet side 16 of the drying rotor bymeans 6 in the form of a tube 24 and a second end portion connection 25for the cooled, dehumidified gas stream, which is separated from thefirst end portion connection 18 for the moist gas stream 2. As indicatedabove, also a part of the cooled, dehumidified gas stream may be mixedwith the moist gas stream 2 via means 7 (not shown), for instance byconnecting a conduit or tube from the cooler 5 or the tube 24 to theinlet connection 18. Alternatively, the cooled dehumidified gas streammay partly mingle with the moist gas stream in connection with naturalpressure equalizing.

The sectors where the first and second, respectively, end portionconnection 18, 25 connects to the inlet side 16 can be separated bymeans of seals 28, for instance thin rubber moldings or squeegees; FIG.7 shows an enlarged area of the collection container 19 in FIG. 4 at itsconnection to the drying rotor where seal 28 is illustrated. The seals28 are, however, not necessary for separating the cooled, dehumidifiedgas stream from the moist gas stream 2, since the moist gas stream isdirected toward its sector and is sucked through the drying rotor bymeans of a fan (not shown). Another advantage of not using seals is thatunbalances that arise as a consequence of pressure differences betweenthe cooled, dehumidified gas stream and the moist gas stream 2 areleveled out. In order to further improve the pressure equalizing, gaps26, 27 may be arranged in the first and/or second end portion connection18, 25 for the moist gas stream and the cooled, dehumidified gas stream,respectively. In the case where seals 28 are used to eliminate orminimize leakage between the gas streams, the first and/or second endportion connection 18, 25 may be provided with openings to allowpressure equalizing.

As mentioned above, the components that connect to the drying rotor onthe inlet and/or the outlet side 16, 17 may be contained in a shell orhousing (not shown). Leakage losses on the inlet and/or the outlet side16, 17 will then build up a pressure inside the housing that counteractsfurther leakage. Furthermore, the housing contributes to the second endportion connection 25 for the cooled dehumidified gas stream not beingstrictly required, but the cooled dehumidified gas stream that isreturned to the inlet side 16 is directed to the area of the dryingrotor that is not embraced by the first end portion connection 18 forthe moist gas stream and the sector 11 of the stream of regeneration gas3. This is illustrated in FIG. 6.

FIG. 8 illustrates a second embodiment of a sorption drying systemaccording to the present invention. Here, the system comprises acollection container 29 that corresponds to the collection container 19.The difference is that the collection container 29 comprises threeessentially equally large sectors connected to the outlet side 17 of thedrying rotor by means of seals 28 for receiving the dehumidified gasstream and directing it further to the cooler 5. The number of sectorsis, however, not limited to three, but may be varied to achieve anoptimal cooling of the drying rotor. After cooling, the cooled,dehumidified gas stream is directed to the inlet side 16 of the dryingrotor via a returning container 30. Also the returning container 30comprises three sectors connected to the inlet side 16 of the dryingrotor by means of seals 28, which are illustrated in FIG. 9 by theenlarged area of the returning container 30 in FIG. 8.

The three sectors of the returning container 30 are arranged inessentially the same positions on the inlet side 16 as the three sectorsof the collection container 29 on the outlet side 17 so that the sectorsare axially aligned with each other. The moist gas stream 2 is thendirected through the remaining sectors of the drying rotor, separatedfrom the sectors of the cooled, dehumidified gas stream. Thisconfiguration allows increased flow rate of the cooled, dehumidified gasstream for efficiently cooling down the drying rotor along itsrevolution, which gives an improved drying performance. Anotherconceivable solution is that the direction of flow of the cooleddehumidified gas stream is opposite the direction of flow of the moistgas stream through the absorbent mass 1. This can be achieved by meansof, for instance, fans.

FIGS. 10 and 11 depict a sorption drying system in accordance withanother embodiment. Similar parts are labeled with the same referencenumerals for the sake of clarity. According to this version, a mass ofabsorbing material 1 is provided having an inlet side and an outletside. The inlet side is divided into three (3) different inlet areas,herein designated as A, B and C, respectively. A heated regeneration gasstream is directed to or is collected from a first inlet regenerationarea (A), a deflected dehumidified gas stream is directed to a secondinlet area (B), while a humid gas stream is directed to a third inletarea (C) of the mass of absorbing material 1.

The outlet side of the mass of absorbing material 1 is further dividedinto four (4) different outlet areas, herein designated as a, b, c andd, respectively. According to this embodiment, the mass of absorbingmaterial 1 is in a cylindrical form wherein each of the inlet areas (A,B, C) and each of the outlet areas (a, b, c, d) essentially have theshape of a circular sector. Moreover, the mass of absorbing material iscontained in a housing (not shown in FIGS. 10 and 11) but similar tothat previously shown and preferably an air-proof housing, the mass ofabsorbing material having the form of a drying rotor that is adapted torotate about a central axis. According to this embodiment, at least oneof the inlet areas (A, B, C) and/or at least one of the outlet areas (a,b, c, d) is separated from its neighboring area by seals, such as 27,28, previously discussed.

Additionally, a collection container is arranged on the outlet side ofthe mass of absorbing material 1. The outlet areas a, b, c and d areprovided as circular sectors in which the regeneration gas stream iscollected from or is directed to a first outlet area (a). A first partof the deflected dehumidified gas stream is collected from a secondoutlet area (b) and a second part of the dehumidified gas stream iscollected from a third outlet area (c). The deflected dehumidified gasstream is directed out of the drying system as a user dehumidified gasstream. A third part of the deflected dehumidified gas stream iscollected together with the humid gas stream at a fourth outlet area(d). In this configuration, the first part of the deflected dehumidifiedgas stream collected from the second outlet area (b) together with thethird part of the deflected dehumidified gas stream and the humid gasstream collected from the fourth outlet area (d) is deflected by means(not shown) as recirculation to the second inlet area (B) as thedeflected dehumidified gas stream. According to this embodiment, thefirst inlet regeneration area (A) has an area that is different thanthat of the first outlet area (a) and is defined by a first end portionconnection.

Optionally and as shown in FIGS. 10 and 11, a cooler 5 can be providedfor cooling the deflected dehumidified gas stream from the outlet sideof the mass of absorbing material 1 before entering the second inletarea (B).

According to this embodiment, the first end portion connection isarranged on the inlet side of the drying rotor in order to direct thehumid gas stream into the drying rotor. More specifically, the first endportion connection is shaped so that the humid gas stream is directedinward toward only a first end portion area of the drying rotor, suchthat the humid air stream is arranged to flow through a part of thedrying rotor corresponding to the sector defined by the first endportion and to be dehumidified in the drying rotor. According to thisembodiment (as well as the preceding embodiments), the first end portionconnection corresponds to a connector on the IN-side of the drying rotorcovering the inlet area C for the humid gas stream. This termcorresponds substantially with the first end portion connection 18 inFIG. 5.

The collection container is arranged on the outlet side of the dryingrotor to cover a sector of the drying rotor that is essentially as largeas the sector defined by the first end portion connection. Thecollection container is further arranged to deflect the dehumidified gasstream from the outlet side of the drying rotor. For example, a fan canbe situated between the collection container and the cooler 5. Accordingto this embodiment, the collection container is placed so that thesector covered by the collection container essentially corresponds tothe sector defined by the first end portion connection on the inlet sideof the drying rotor toward which the humid gas stream is directed.

According to this embodiment, the third inlet area (C) is situatedessentially immediately before the first inlet area (A) in the directionof rotation of the mass of absorbing material 1.

A second end portion connection is arranged on the inlet side of thedrying rotor and separate from the first end portion connection for thehumid gas stream for purposes of returning the cooled deflecteddehumidified gas stream to the inlet side of the drying rotor. Thesecond end portion connection, for purposes of this embodiment (andpreceding embodiments) corresponds to a connector on the IN-side of thedrying rotor covering the inlet area B for the deflected dehumidifiedgas stream. This feature corresponds for purposes of this discussionwith the connection 25 as depicted in FIG. 5. The circular sector thatis defined by the first end portion connection is situated essentiallyimmediately before the regeneration inlet area (A) in the direction ofrotation of the mass of absorbing material 1. According to thisconfiguration, the cooled deflected dehumidified gas stream is arrangedto flow through the drying rotor in a second sector defined by thesecond end portion connection and separated from the sector defined bythe first end portion connection containing the humid gas stream.

According to this embodiment, the third outlet area (c) is essentiallyas large as the third inlet area (C). In addition, the collectioncontainer can comprise a second collection sector arranged immediatelyafter the regeneration sector.

The herein described system can further comprise a valve situated at aninlet connection or an outlet connection for the stream of regenerationgas for regulating the pressure of the stream of regeneration gas.Alternatively, a valve can be situated at the inlet side or the outletside of the mass of absorbing material 1 for regulating the pressure ofthe humid gas stream. A regulating fan can further be provided forvarying the flow of the stream of regeneration gas through the mass ofabsorbing material or for varying the flow of the humid gas streamthrough the mass of absorbing material.

Still referring to FIGS. 10 and 11, a method for dehumidification of agas stream in the sorption drying system comprising the mass ofabsorbing material 1 having an inlet side and an outlet side comprisesthe following steps. A humid gas stream is directed into the mass ofabsorbing material through a first end portion connection arranged onthe inlet side of the mass of absorbing material. The first end portionconnection is shaped such that the humid gas stream is directed inwardtoward the a sector-shaped area of the mass of absorbing material, suchthat the humid gas stream flows through a part of the mass of absorbingmaterial corresponding to the sector defined by the first end portionconnection and is dehumidified.

A heated stream of regeneration gas is directed through a regenerationsector of the mass of absorbing material, wherein the regenerationsector is separated from the sector defined by the first end portionconnection.

The dehumidified gas stream is deflected from the outlet side of themass of absorbing material by means of a collection container arrangedon the outlet side of the mass of absorbing material in order to over asector of the mass of absorbing material that is essentially as large asthe sector defined by the first end portion connection. The collectioncontainer is placed so that the sector covered by the collectioncontainer essentially corresponds to the sector defined by the first endportion connection on the inlet side of the mass of absorbing materialtowards which the humid gas stream is directed.

The deflected dehumidified gas stream is returned to the inlet side ofthe mass of absorbing material by means of a second end portionconnection arranged on the inlet side of the mass of absorbing materialseparate from the first end portion connection for the humid gas stream.

The mass of absorbing material is in the form of a drying rotor having acylindrical configuration and circular shape that is adapted to rotateabout a central axis. The end portions of the drying rotor have theshape of circular sectors into and from which sectors of the gas streamsare directed.

According to this method, the sector defined by the first end portionconnection is situated essentially immediately before the regenerationsector in the direction of rotation of the drying rotor. According toone version of the method, the deflected dehumidified gas stream isdirected through a cooler in which the cooled deflected dehumidified gasstream is directed through the drying rotor in a second sector definedby the second end portion connection and separated from the sectordefined by the first end portion connection containing the humid gasstream.

The pressure of the stream of regeneration gas and/or the humid gasstream can be regulated in such a way that the pressure of the stream ofregeneration gas is essentially equal to, but always lower than thepressure of the humid gas stream.

The invention is of course not limited to the embodiments that areillustrated here, but may be varied within the scope of protection thatis defined by the claims.

The invention claimed is:
 1. A sorption drying system fordehumidification of a humid gas stream, said system comprising: a massof absorbing material having an inlet side and an outlet side; the inletside being divided into three different inlet areas (A,B,C) wherein aheated regeneration gas stream is either directed to or collected from afirst inlet regeneration area (A), a deflected dehumidified gas streamis directed to a second inlet area (B) and a humid gas stream isdirected to a third inlet area (C), the outlet side being divided intofour different outlet areas (a,b,c,d); a collection container arrangedon the outlet side of the absorbing material, in which the regenerationgas stream is collected from or the regeneration gas is directed to afirst outlet area (a), collecting a first part of the deflecteddehumidified gas stream from a second outlet area (b), collecting asecond part of the deflected dehumidified gas stream from a third outletarea (c) and directing the deflected dehumidified gas stream out fromthe drying system as a user dehumidified gas stream, collecting a thirdpart of the deflected dehumidified gas stream together with the humidgas stream, from a fourth outlet area (d), wherein the first part of thedeflected dehumidified gas stream from the second outlet area (b)together with the third part of the deflected dehumidified gas streamand the humid gas stream from the fourth outlet area (d) is deflected asa recirculation to the second inlet area (B) as the deflecteddehumidified gas stream.
 2. The sorption drying system according toclaim 1, wherein the first inlet regeneration area (A) has a differentarea than the first outlet area (a), which is defined by a first endportion connection.
 3. The sorption drying system according to claim 2,wherein the system further comprises a cooler for cooling the deflecteddehumidified gas stream from the outlet side of the absorbing materialbefore entering the second inlet area (B).
 4. The sorption drying systemaccording to claim 1, wherein the mass of absorbing material is in acylindrical form and each of the inlet areas (A, B, C) and each of theoutlet areas (a, b, c, d) substantially have the shape of a circularsector.
 5. The sorption drying system according to claim 4, wherein themass of absorbing material is contained in and has the form of a dryingrotor adapted to rotate about a central axis.
 6. The sorption dryingsystem according to claim 5, wherein the first end portion connection isarranged on the inlet side of the drying rotor to direct a humid gasstream into the drying rotor, wherein the first end portion connectionis shaped so that the humid gas stream is directed inward toward only asector part of the first end portion area of the drying rotor, such thatthe humid gas stream is arranged to flow through a port of the dryingrotor corresponding to the sector defined by the first end portionconnection and to be dehumidified in the drying rotor.
 7. The sorptiondrying system according to claim 6, wherein the collection container isarranged on the outlet side of the drying rotor that is substantially aslarge as the sector defined by the first end portion connection anddeflect a dehumidified gas stream from the outlet side of the dryingrotor, wherein the collection container is placed so that the sectorcovered by the collection container substantially corresponds to thesector defined by the first end portion connection on the inlet side ofthe drying rotor toward which the humid gas stream is directed.
 8. Thesorption drying system according to claim 5, wherein the third inletsector (C) is situated substantially immediately before the first inletsector (A) in the direction of rotation of the drying rotor.
 9. Thesorption drying system according to claim 5, wherein a second endportion connection arranged on the inlet side of the drying rotorseparate from the first end portion connection for the humid gas streamfor returning the cooled deflected dehumidified gas stream to the inletside of the drying rotor, wherein the sector defined by the first endportion connection is situated substantially immediately before theregeneration sector in the direction of rotation of the drying rotor,and wherein the cooled deflected dehumidified gas stream is arranged toflow through the drying rotor in a second sector defined by the secondend portion connection and separated from the sector defined by thefirst end portion connection and containing the humid gas stream. 10.The sorption drying system according to claim 4, wherein the thirdoutlet sector (c) is substantially as large as the third inlet sector(C).
 11. The sorption drying system according to claim 3, furthercomprising a fan situated between the collection container and thecooler.
 12. The sorption drying system according to claim 5, wherein thecollection container comprises a second collection sector arrangedimmediately after the regeneration sector.
 13. The sorption dryingsystem according to claim 1, further comprising: a valve situated at aninlet connection or outlet connection for the stream of regeneration gasfor regulating the pressure of the stream of regeneration gas, and avalve situated at the inlet side or outlet side of the mass of absorbingmaterial for the humid gas stream for regulating the pressure of thehumid gas stream.
 14. A sorption drying system for dehumidification of ahumid gas stream, said system comprising: a mass of absorbing materialhaving an inlet side and an outlet side, wherein the inlet side isdivided into three different inlet areas (A, B, C) wherein a heatedregeneration gas stream is either directed to or collected from a firstinlet regeneration area (A), a deflected dehumidified gas stream isdirected to a second inlet area (B) and a humid gas stream is directedto a third inlet area (C), the outlet side being divided into fourdifferent outlet areas (a, b, c, d); a collection container arranged onthe outlet side of the absorbing material, collecting the firstregeneration gas stream from or directed the regeneration gas to a firstoutlet area (a), collecting a first part of the deflected dehumidifiedgas stream from a second outlet area (b), collecting a second part ofthe deflected dehumidified gas stream from a third outlet area (c) anddirecting the deflected dehumidified gas stream out from the dryingsystem as a user dehumidified gas stream, collecting a third part of thedeflected dehumidified gas stream together with the humid gas streamfrom a fourth outlet area (d), wherein the sorption drying systemfurther comprises: a valve situated at an inlet connection or outletconnection for the stream of regeneration gas for regulating thepressure of the stream of regeneration gas, and a valve situated at theinlet side or outlet side of the mass of absorbing material for thehumid gas stream for regulating the pressure of the humid gas stream.15. The sorption drying system according to claim 14, further comprisinga fan for varying the flow of the stream of regeneration gas through themass of absorbing material.
 16. The sorption drying system according toclaim 14, further comprising a fan for varying the flow of the humid gasstream through the mass of absorbing material.
 17. The sorption dryingsystem according to claim 14, wherein the parts of the drying systemthat comprise the mass of absorbing material are built in an air-proofhousing.
 18. The sorption drying system according to claim 14, whereinat least one of the inlet areas (A, B, C) and at least one of the outletareas (a, b, c, d) is separated from its neighboring area by seals. 19.The sorption drying system according to claim 1, wherein at least one ofthe inlet areas (A, B, C) and at least one of the outlet areas (a, b, c,d) is separated from its neighboring area by seals.
 20. A method fordehumidification of a gas stream in a sorption drying system comprisinga mass of absorbing material having an inlet side and an outlet side,wherein the method comprises the steps of: directing a humid gas streaminto the mass of absorbing material through a first end portionconnection arranged on the inlet side of the mass of absorbing material,wherein the first end portion connection is shaped so that the humid gasstream is directed inward toward a sector-shaped area of the mass ofabsorbing material, such that the humid gas stream flows through a partof the mass of absorbing material corresponding to the sector defined bythe first end portion and is dehumidified; directing a heated stream ofregeneration gas through a regeneration sector of the mass of absorbingmaterial, wherein the regeneration sector is separated from the sectordefined by the first end portion connection; deflecting the dehumidifiedgas stream from the outlet side of the mass of absorbing material bymeans of a collection container arranged on the outlet side of the massof absorbing material to cover a sector of the mass of absorbingmaterial that is substantially as large as the sector defined by thefirst end portion connection, wherein the collection container is placedso that the sector defined by the first end portion connection on theinlet side of the mass of absorbing material toward which the humid gasstream is directed; and returning the dehumidified gas stream to theinlet side of the mass of absorbing material by means of a second endportion connection arranged on the inlet side of the mass of absorbingmaterial separate from the first end portion connection for the humidgas stream.
 21. The method according to claim 20, wherein the mass ofabsorbing material is in the form of a drying rotor of a substantiallycircular shape adapted to rotate about a central axis, wherein endportions of the drying rotor are formed in the shape of circular sectorsinto and from which sectors of the gas stream are directed.
 22. Themethod according to claim 21, wherein the sector defined by the firstend portion connection is situated immediately before the regenerationsector in the direction of rotation of the drying rotor.
 23. The methodaccording to claim 22, wherein the deflected dehumidified gas stream isdirected through a cooler, the method further comprising the step ofdirecting the cooled deflected dehumidified gas stream through thedrying rotor in a second sector defined by the second end portionconnection and separated from the sector defined by the first endportion connection and containing the humid gas stream.
 24. The methodaccording to claim 20, further comprising the step of regulating thepressure of the stream of regeneration gas or the humid gas stream insuch a way that the pressure of the stream of regeneration gas isessentially equal to, however always lower than, the pressure of thehumid gas stream.